Protective devices in distribution systems are utilized to optimize the network reliability and to avoid
or minimize the damaging in the circuits and the instruments. The considered method and the level of the
protection, is under various factors. One of the most important tools in selecting the type of the distributed
system's equipment is evaluation of the short-circuit current correctly. In addition, this analysis is very
noticeable in allocation and setting the protective devices in any networks. In this study, a novel method is
presented in order to analysis the unsymmetrical fault occurs in the low voltage distributed networks. Initially,
regarded to a complete model, the line impedances such as overhead and underground line impedances, in the
network are computed and the methodology and modeling associated with two relationship matrices BIBC and
BCBV is described. Then, the calculations method for the fault's current is evaluated by defining a new model
consists of four matrices. Therefore, a program is provided for determination of short-circuit current, identifying
the branches which carry short-circuit current and the results of it on the voltage profile, according to presented
equations and Delphi software. At the end, all connection types and their results on the network are evaluated
on a real low voltage network.